Friday, March 24. 2006

I found this great article on TechnologyReview.com that reviews the possible alternatives to using IVF embryos or creating cloned embryos for embryonic stem cells.

Let me give the run down with commentary. Alternative #1:

Markus Grompe, director of the Oregon Stem Cell Center at Oregon Health and Science University in Portland, hopes to find a way around the debate by producing cloned cells that have all the properties of embryonic stem cells -- but don't come from embryos.

His plan involves a variation on the cloning procedure that produced Dolly the sheep. In the original procedure, scientists transferred the genetic material from an adult cell into an egg stripped of its own DNA. The egg's proteins reprogrammed the adult DNA, creating an embryo genetically identical to the adult donor. Grompe believes that by forcing the donor cell to produce a protein called nanog, which is normally found only in embryonic stem cells, he can alter the reprogramming process so that it never results in an embryo. Instead, it would yield a cell with many of the characteristics of an embryonic stem cell.

And alternative #2:

Last fall, MIT biologist Rudolf Jaenisch and graduate student Alexander Meissner showed that by turning off a gene called CDX2 in the nucleus of an adult cell before transferring it into a nucleus-free egg cell, they could create a biological entity unable to develop into an embryo -- but from which they could still derive normal embryonic stem cells.

I believe that these would be part of the Oocyte Assisted Reprogramming (OAR) family of alternatives that are called altered nuclear transfer (ANT) There is debate in the Catholic community on whether these are ethical. Would these techniques create a biological artifact that is simply a ESC generator or a diabled embryo that can never fully develop? The jury is still out. I am not a fan of either of these because they still need eggs for reprogramming like SCNT (regular cloning) and as I have repeated stated that puts women at risk for exploitation.

Alternative #3:

Also last fall, researchers at Advanced Cell Technology in Worcester, MA, grew embryonic stem cells using a technique that resembles something called preimplantation genetic diagnosis (PGD). PGD is used to detect genetic abnormalities in embryos created through in vitro fertilization; doctors remove a single cell from an eight-cell embryo for testing. The researchers separated single cells from eight-cell mouse embryos, but instead of testing them, they put each in a separate petri dish, along with embryonic stem cells. Unidentified factors caused the single cells to divide and develop some of the characteristics of stem cells. When the remaining seven-cell embryos were implanted into female mice, they developed into normal mice.

This one is called embyro biospy and it sounds good but it is clearly unethical. The biopsy puts the life of the embryo at risk with no corresponding benefit to the embryo. Also, creating embryos outside the unitive act of conjugal love in a petri-dish is a big no-no.

Saving the best for last, alternative #4:

And Harvard University biologist Kevin Eggan believes it may be possible to create stem cells whose DNA matches a specific patient's by using existing stem cells stripped of their DNA to reprogram adult cells.

This technique, while still early in development, seems to me to be the most ethical. It uses existing stem cells to reprogram an adult cell back to a pluripotent state, not an egg and it doesn't create anything that looks like an embryo.

The article ends on a chilling note. Some question why, with the common pratice of IVF, would we even try to find an alternative to real embryos for ESCs?:

"We've already decided as a society that it's perfectly okay to create and destroy embryos to help infertile couples to have babies. It seems incredible to me that we could say that that's a legitimate thing to do, but we can't do the same thing to help fight diseases that kill children," says David Magnus, director of the Stanford Center for Biomedical Ethics.

I am afraid he has a point. Once again, the Church's teaching on reproduction without sex, i.e. IVF, has far reaching wisdom.

Saturday, February 11. 2006

After reading this great synthesis by Chip Bennett at cb.blog I realized that altered nuclear transfer (ANT) maybe a Trojan horse.

First, let me explain altered nuclear transfer. Dr. William Hurlbut of Stanford, in an effort to present alternatives to somatic cell nuclear transfer (SCNT) better known as cloning, came up with the idea for ANT. In ANT, the somatic cell nucleus is altered before it is placed in the emptied egg, creating what Dr. Hurlbut calls a biological artifact, not a human embryo. This biological artifact could then be used to grow embryonic stem cells. I have written on ANT before.

I believe that Dr. Hurlbut should be commended for his efforts to provide an alternative to cloning to obtain "patient-specific" embryonic stem cells, but there is disagreement on whether this is ethical research. Some worry that ANT would create a crippled embryo instead of a biological artifact. And, ANT still needs eggs like SCNT.

But, I do not want to discuss the merits and ethical implications of ANT right now. I want to discuss how ANT is being used as a way to pave the way to SCNT, instead of diverting the road away from it as intended.

Awhile back, I was alerted to this approach by a reader who sent me an editorial in a Catholic diocese newspaper. (Thanks Charlie!) I can't print it here as it was by subscription only, but I will relate the upshot. The Catholic paper advocated lifting their state's ban on cloning to allow for ANT research. It is true many Catholics are in disagreement over ANT, but lifting the ban on cloning would also allow for SCNT which the Church explicitly condemns. I thought that this editorial was not only strange but also utterly misleading. I just chalked it up to a misunderstanding by the author.

Enter Sen. Jim Talent, who has retracted his support for a ban on all human cloning (SCNT) in the Senate. From the Kansas City Star: (which is pretty much sick of the Clone the Truth campaign, because all of their articles have errors, this one is no exception)

Sen. Jim Talent on Friday withdrew as co-sponsor of a bill that would ban all human cloning and make it a crime for anyone to take part in the process.

In a speech on the Senate floor, Talent said the alternative research made the bill unnecessary. The new research - called altered nuclear transfer - would provide common ground for people on all sides of the issue, he said.

Like the Catholic newspaper, Sen. Talent has given de facto support to SCNT by not moving to ban it citing his support for ANT as the reason.

This is crazy! Of course, a federal ban on SCNT is still "necessary" whether you support ANT or not. Also, if Dr. Hurlbut is correct, ANT is not therapeutic cloning in the strict sense because it does not create a cloned embryo, and therefore it would not be subject to the cloning ban being debated in the Senate. And, I am sure Talent's reasoning for taking back his support for a ban on cloning was not what Dr. Hurlbut had in mind when he envisioned ANT.

Let's get a ban on SCNT which for sure creates a cloned embryo and could lead to reproductive cloning and then discuss the merits of ANT later.

Because of the widespread confusion surrounding cloning and its alternatives, I have a sinking feeling that we will be seeing more this "Trojan horse" reasoning in the future.